The change for publishers, though, is far more profound than a simple change in delivery mechanism would suggest. Publishers, indeed all commercial media in our lifetime, have been defined primarily by format. Some do books; some do magazines; some do newspapers. Others called producers do movies or television or radio. The capital and skill set requirements for a format effectively channeled the media company. For the most part, big media was not topic- or subject-specific; it was format-specific.
But when the exchange between publisher and content consumer becomes a file, rather than a book or magazine or movie or TV show, then format becomes irrelevant. A file can hold any of the formats we have historically thought of: text, photographs, diagrams, maps, video, audio. A file can also hold games and productivity software. So the publisher that is limited by the formats of the 20th century will not be competitive in the cloud-and-screen based media exchange of the future.
What all of this means, taken together, is that the successful publisher of the year 2030 will own a web community which is both a principal source of content and provides the audience for it. The community will not be content-centric alone; but we aren’t getting into that in more detail right now because sketching out the whole concept for “vortals” is “out of scope” for this exercise.
The publisher who owns “knitting”, or perhaps “knitting sweaters”, will develop and curate the content and control access to the audience just as surely as a major publisher has controlled access to bookstores shelves or a newspaper publisher to newsstand sales in our lifetimes.
If you're wondering why everyone in business these days is obsessed with building communities, well, this is why.